Microphones are transducers that convert acoustic energy into electronic energy. Many transduction principles have been developed, including the piezoelectric microphone, the capacitive microphone and the contact microphone.
In the prior art, the majority of silicon microphones are based on the capacitive detection principle. These microphones are also called as the capacitive microphone or condenser microphone.
A condenser microphone is disclosed in P. R. Scheeper, et al, A review of silicon microphone, Sensors and Actuators, A44, 1994, 1-11, which is hereby incorporated herein by reference. FIG. 1 shows the condenser microphone, which includes a diaphragm 11, an air gap 12, a back plate 13 and a back chamber 15. The back plate 13 has acoustic holes 14 connecting the air gap 12 and the back chamber 15.
The Micro-Electro-Mechanical Systems, or MEMS, refers to a miniaturized mechanical and electro-mechanical member (i.e., devices and structures) that is made using the techniques of micro-fabrication. A MEMS microphone is a microphone which is based on MEMS technology.
Therefore, there is a demand in the art that a new capacitive MEMS microphone shall be proposed to address at least one of the problems in the prior art.